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Abstract No. 118: A comparison of methods for tracking RFA probes and sensitivity to RF field and temperature

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  trode (Boston Scientific) was used in 15 procedures,whereas a straight Cool-tip electrode (Covidien) was used in5 procedures. Primary treatment effectiveness was 18/20(90%). There was a 1.2 cm diameter residual enhancing areain the patient who had 2 RFA procedures, which did notchange on US follow-up during subsequent uneventfulpregnancy or on CT after delivery. In another patient whobecame pregnant after RFA, there was no change in theablation zone and no tumor enhancement. A single compli-cation (subcapsular liver hematoma) was managed conser-vatively. There were no reports of pain, bleeding, or malig-nant transformation beyond the first week following RFA.Mean follow-up was 39 months (range 1-83). Conclusion:  RFA is safe and effective in the treatment of hepatocellular adenoma, and may be considered to replacesurgical resection in selected patients. Scientific Session 13IO Guidance and EndpointsTuesday, March 16, 201010:00 AM - 12:00 PMRoom: 5/6 10:00 AM Abstract No. 116S.I.R.I.O.: Intra-operating robotic pursuing system: Ini-tial results R.F. Grasso, G. Luppi, F. Carcione, E.E. Faiella,C. Piccolo, B. Beomonte Zobel;  Campus Biomedico Uni-versity, Rome, Italy.  Purpose:  To assess the clinical benefit of a robotic systemfor procedures of lung interventional radiology (S.I.R.I.O.)By an infrared sensor, it indicates patient and needle posi-tion and their movements in space. SIRIO doesn’t useionizing radiation  Materials and Methods:  A prospective study of 36 consecu-tives patients was performed. The study was approved by theEthical Commettee of our University. The last 18 patientsunderwent to traditional biopsy and the first 18 cases treatedwith SIRIO were examinated. Each patient was informedabout the procedure. We collected data about: duration of theprocedure, from the first puncture of local anesthesia to lesionachievement; number of performed scans; x-rays dose to reachthe lesion; pointing error in the first needle piling. The cuta-neous sensor was not placed on the first patient.  Results:  We obtained the 100% of technical success, that isthe reaching of the lesion. A statistical analysis with tStudent test was performed. A p value less than 0.05 wasinterpreted as statistically significant. Without consideringthe first patient, we obtained that, as for as the average of lesion reaching time, it was 14(   /-7) minutes for SIRIO, vs25 (   /-12) minutes for traditional biopsies. For these datathe p value was less than 0.05 (0.0451). The average of scans number was 3.4 (   /-1.5) for SIRIO vs 6 (   /-4). Asfor as the average dose to reach the lesion, in DLP it was256.25 (   /-149) for SIRIO, vs 446 (   /-433), in mAs it wasrespectivelyof1617(   /-1043)and2835(   /-3108).Aboutthepointing error in the first needle piling, calculated as diver-gence angle between the ideal path and the real one, theaverage error was 9° for SIRIO vs 24° for traditional biopsy. Conclusion:  SIRIO helps the operator to reach the target, ina reduced time and with a reduced number of scans and aless dose of radiations. From the first puncture, it indicatesthe correct needle path, with a greater precision than thetraditional methodics. Thorax model is good approximatedto real thorax movements. The precision of the system infields with a reduced motion of the target, ike bone andmuscles, will be evaluated. 10:12 AM Abstract No. 117Accuracy of RFA probe insertion using camera-on-nee-dle versus electromagnetic tracking V. Saxena, A. Beck, A. Kapoor, B.J. Wood;  National Institutes of Health, Radiology and Imaging Sciences, Cen-ter for Interventional Oncology, Bethesda, MD.  Purpose:  To evaluate and compare first-pass accuracy of RFA probe insertion assisted by camera-on-needle versuselectromagnetic (EM) guidance in phantoms.  Materials and Methods:  A 17Gx15cm single RFA probe(Covidian, Boulder, CO) was inserted into an interventionalphantom (CIRS Inc., Norfolk, VA) using camera-on-needleor EM guidance. Both systems consist of a mobile unit withcomputer, graphical user interface and fiducial markers. TheActiSight™ (ActiViews, Haifa, Israel) system uses a sensorcamera affixed beneath the handle of the RFA probe,whereas the PercuNav (Traxtal Inc., Toronto, ON) systemuses a sensor coil integrated at the tip of a hollow outercannula with an adjacent EM field generator. Pre-proceduralCT images of the phantom containing targets and fiducialmarkers were obtained, imported and used for path planningand guidance. The needle was inserted using navigation inone continuous pass. Once the target was reached, a verifi-cation CT scan was obtained, and the reported and actualneedle-tip distance-to-target (DTT) measurements were re-corded and compared. System error was the differencebetween the system’s reported and actual DTT.  Results:  Target depths ranged from 48.8-71.0mm for Acti-Sight™ (N  11) and 48.7-72.3mm for PercuNav (N  11). Forfirst-pass, continuous needle insertion, the mean actual DTTvalues were comparable (3.84mm   1.80mm and 3.37mm  1.76mm for ActiSight™ and PercuNav, respectively). Sys-tem errors, not accounting for vector direction (non-direc-tional) were also similar (2.91mm   1.38mm and 1.61mm  1.54mm for ActiSight™ and Traxtal, respectively). Conclusion:  Both camera-on-needle tracking and EM-tracked cannula systems enable the target to be reached witha single, continuous pass with high accuracy and low systemerror in stationary phantoms. These encouraging resultswarrant further study and could address shortcomings inRFA probe insertion when used in conjunction with stan-dard CT and US imaging guidance. Improved accuracy andreduced number of probe passes may theoretically decreasecomplications and improve clinical outcomes in some set-tings, such as large composite ablations in which needleplacement accuracy is paramount. 10:24 AM Abstract No. 118A comparison of methods for tracking RFA probes andsensitivity to RF field and temperature F. Razjouyan  1 , A. Kapoor  1 , N. Glossop  2  , J. Kruecker  3  ,S. Xu  3  , A. Viswanathan  1 , O.A. Chiesa  4  , J.W. Karanian  4  ,W. Pritchard  4  , E. Levy  1 , A. Venkatesan  1 , L. Solbiati  5  ,B.J. Wood  1 ;  1  National Institute of Health, Bethesda, MD; 2 Traxtal Inc., Toronto, ON, Canada;  3 Philips Research North America, Briarcliff, NY;  4 Food and Drug Adminis-tration, Silver Spring, MD;  5 General Hospital of Busto Arsizio, Busto Arsizio, Italy. S46   Purpose:  Demonstrate five different techniques for MedicalGPS or Fusion Imaging Guidance during radiofrequencyablation (RFA), and study the effects of the RFA tempera-ture and radiofrequency (RF) interference on accuracy of electromagnetic (EM) tracking near the ablation and RFfield.  Materials and Methods:  Spatial tracking of the US probe,the RFA probe and registering the tracking coordinatesystem with the CT/MRI coordinate system enables real-time fusion of US image with complementary imagingmodalities for intra-procedural guidance. The spatial,temporal, temperature dependant accuracy of the trackingdevices affects the quality of the real-time fusion. Fivedifferent methods, listed below, to track the location of different ablation hardware were evaluated. All methodswere based on EM tracking, but differed in the location of the tracking sensor coil - “Antenna” of the GPS device,namely: 1) Internal sensor coil in RFA probe tip 2) Anintroducer with a coaxial stylet that has an internal sensorcoil at the tip 3) Internal hollow sensor coil embedded inouter cannula of coaxial sheath 4) Internal sensor coil inguide needle tip as part of a guider needle, parallel toRFA probe; and 5) external sensor coil at hub of the RFAprobe.  Results:  Three methods were employed successfully in pa-tients (one method in pig, and one in phantoms) providingmeans of multimodality guidance. Very mild, clinicallyirrelevant deviations in position (avg. 0.5mm, std. dev.0.3mm at 80deg C) and orientation (avg. 0.3deg, std. dev.0.3deg at 80deg C), in addition to the room temperatureerror were reported during high temperature ablations withthe method #3 (hollow internal sensor coil). Conclusion:  High temperatures do not significantly alterinternal tracking and methods evaluated can be applied tomultiple commercial RFA systems. All methods, exceptmethod #1 (sensor coil in probe tip), do not require modi-fications to the RFA system. 10:36 AM Abstract No. 119Computed analysis of 3D cone beam CT angiographyfor determination of tumor-feeding vessels duringchemo-embolization: A pilot study F. Deschamps  1 , S.B. Solomon  2  , A. Hakime  1 , P.P. Rao  1 ,R.H. Thornton  2  , V. Kuoch  1 , T. de Baere  1 ;  1 Gustave Roussy Institut, Villejuif, France;  2  Memorial Sloan-Ketter-ing Cancer Center, New York, NY.  Purpose:  Evaluation of a software able to determine thetumor-feeding vessels for selective liver trans-arterialchemo-embolization.  Materials and Methods:  Eighteen consecutive trans-arte-rial chemo-embolizations (TACE), performed betweenJanuary and October 2008 for 25 liver tumors (15 hepa-tocarcinomas, 10 neuroendocrine metastases) measuring21 to 96mm, were retrospectively reviewed to determinetumor feeding vessels (TV). For each TACE, an antero-posterior projection angiogram (2D) and 3D rotationalangiogram (3D) had been acquired with injection in thecommon hepatic artery. The determination of TV wasindependently obtained by 3 x-ray technicians using asoftware (S) which automatically determines TV by anal-ysis of 3D cone beam CT angiography (GE Healthcare,Buc, France). The determination of TV was indepen-dently performed by 3 experienced interventional radiol-ogists external to the cases, by reviewing 2D images first,and then the 3D. The “Ground-truth” (GT) for the num-ber and location of TV was obtained by a consensusamong the 3 interventional radiologists who were al-lowed to use any imaging including 2D, 3D and allselective angiograms obtained during the TACE. Numberand location of TV depicted on 2D, 3D, S were comparedto GT in order to define sensitivity of 2D, 3D, S. Durationand degree of agreement for reviewing 2D and 3D and Swere evaluated.  Results:  Sensitivity of 3D (73%) was higher than 2D (64%),p  0.036. The sensitivity of S (93%) was higher than 2Dand 3D (p  0.005). The duration of reviewing 3D wassignificantly higher than 2D: 187 vs. 94 seconds, p  0.0001,or S (135 seconds) (p  0.0001). The degree of agreementbetween the 3 interventional radiologists using 2D and 3Dwere 54% and 62% respectively while it was 82% betweenthe 3 x-ray technicians using S. Conclusion:  Computed determination of tumor-feedingvessels seems accurate and sensitive, with an increasedaccuracy for selective TACE when compared to the use of 2D or 3D imaging alone. Prospective use of software mustbe performed to confirm preliminary data. 10:48 AM Abstract No. 120Imaging guidance with c-arm CT (CACT) for transhe-patic arterial chemoembolization: A prospective, ran-domized study evaluating the impact of CACT on pa-tient radiation exposure A. Tognolini  1,2  , N. Kothary  1 , R. Fahrig  3  ,M. Abdelmaksoud  1 , G.L. Hwang  1 , J.D. Louie  1 ,L. Hofmann  1 , D.Y. Sze  1 ;  1  Interventional Radiology, Stan- ford University, Stanford, CA;  2 UCLA, Los Angeles, CA; 3  Radiology, Stanford University, Stanford, CA.  Purpose:  To evaluate the incremental increase in radiationdose to patients in whom CACT is used in addition to digitalsubtraction angiography (DSA) for imaging guidance dur-ing transhepatic arterial chemoembolization (chemoemboli-zation).  Materials and Methods:  From April to September 2009,32 patients with hepatocellular carcinoma were prospec-tively randomized to undergo chemoembolization usingDSA and CACT (group 1) or DSA alone (Group 2) forimaging guidance. Patients with more than three tumorsor a single tumor  6.5 cm were excluded. Superselectivechemembolization was performed in all patients. Forpatients in Group 1, 3D reconstructed images from acontrast-enhanced CACT, obtained during iodinated con-trast injection into the common or proper hepatic artery,were reviewed, and additional DSA imaging was per-formed as needed. In patients who had prior chemoem-bolizations, an unenhanced CACT was first performed toassess for retained ethiodol. In group 2, standard AP and30°right anterior oblique hepatic DSA was performed.Additional obliquities were obtained as needed. The totalradiation dose (DAP) for guidance (from aortogram tosuperselective catheterization for embolization), volumeof contrast used and procedural time was recorded for allcases.  Results:  The mean DAP for guidance for group 1 was20013.8 (range: 4947.3-38616.3) vs. 17937.3   Gy-m2(range: 3123.8-56236.2) for group 2 (11% increase). Themean number of DSA acquisitions required for guidancewas 4.4 (range: 2-8) in group 1 vs. 6.8 (range: 5-12) ingroup 2. The total fluoroscopy time in group 1 was 24.5 min    S  ci     en t   i    fi  c S  e s si     on sT  UE  S DA Y  S47
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